Haruki hears about Kazusa's moving from her mother, who she hadn't been on good terms with.  He feels betrayed and angrily confronts her.  But his words force open the door to Kazusa's heart, which she had desperately tried to keep closed so that the three of them could stay together.
Wait, why does it bother you so much?
Moment, wieso stört dich das eigentlich so?
Espera, ¿por qué te molesta tanto?
Oye, ¿por qué te molestas tanto?
T’es jaloux, ou quoi ?
Espere por que isso te irrita tanto?